US 6,806,140 B1 · Semiconductor memory device for eliminating floating body effect and method of fabricating the same

Abstract

A semiconductor memory device from which a floating body effect is eliminated and which has enhanced immunity to external noise, and a method of fabricating the same are provided. The memory device includes a semiconductor substrate. A plurality of bit lines are buried in the semiconductor substrate such that the surfaces of the bit lines are adjacent to the surface of the semiconductor substrate. The bit lines are arranged in parallel with one another. A plurality of word lines are formed on the semiconductor substrate so that the word lines cross and are isolated from the bit lines. A plurality of vertical access transistors are formed at individual memory cells where the bit lines and the word lines intersect. Each vertical access transistor includes a first source/drain region, a body region including a vertical channel region and a second source/drain region which are formed sequentially on the bit line. The vertical access transistor contacts a gate insulation layer formed on a portion of one side of the sidewalls of the word line. Body regions including the channel regions of the access transistors are connected to one another to be a single integrated region.

Claims10

Dependent claims

A method of fabricating a semiconductor memory device, comprising:

forming trench regions filled with an insulating material at predetermined intervals, the trench regions being buried in a semiconductor substrate such that they are adjacent to the surface of the semiconductor substrate;
forming a bit line between adjacent trench regions in the semiconductor substrate;
sequentially forming a first insulation layer, a conductive layer for a word line and a mask layer of an insulating material over the resulting structure including the bit line;
forming a word line having the mask layer on its top surface overlying the trench regions;
forming a second insulation layer on the sidewall of the exposed word line;
exposing a portion of the surface of the bit line adjacent to the sidewall of the word line where the word line and the bit line intersect;
forming a first source/drain region material layer on the exposed bit line;
forming a body region material layer on the semiconductor substrate including the first source drain region material layer such that the body region material layer has a predetermined height from the mask layer on the word line;
etching a portion of the body region material layer to form a body region on the first source/drain region material layer;
and
forming a second source/drain material layer on the body region.

8 more elements

A method of fabricating a semiconductor memory device that does not have a floating body effect, comprising the steps of:

forming trench regions filled with an insulating material at predetermined intervals, the trench regions being buried in a semiconductor substrate such that they are adjacent to the surface of the semiconductor substrate;
forming a bit line between adjacent trench regions in the semiconductor substrate;
sequentially forming a first insulation layer and a conductive layer for a word line over the resulting structure including the bit line;
forming a word line on the first insulation layer;
forming a second insulation layer on the word line;
exposing a portion of the surface of the bit line adjacent to the sidewall of the word line where the word line and the bit line intersect;
forming a first source/drain region material layer on the exposed bit line;
forming a body region material layer on the semiconductor substrate including the first source drain region material layer such that the body region material layer is positioned higher than the word line;
planarizing the semiconductor substrate including the body region material layer until the surface of the word line is exposed;
forming a third insulation layer on the surface of the planarized semiconductor substrate;
etching a portion of the third insulation layer to expose the portion of the body region material layer overlying the first source/drain region material layer;
etching a portion of the body region material layer to a predetermined depth using the etched third insulation layer as an etching mask;
and
forming a second source/drain material layer on the etched body region material layer.

11 more elements

Dependencies are inferred from the claim text.

Semiconductor memory device for eliminating floating body effect and method of fabricating the same

Life of this patent

Semiconductor memory device for eliminating floating body effect and method of fabricating the same

Life of this patent

Abstract

Claims10